COL3A1 and neoplasm: Subgroup 3 tumors (and some subgroup 5 tumors) also showed high expression of several collagen genes (COL12A1, COL3A1, COL6A1, COL1A1, and COL5A2), and high expression of collagen genes has been associated with poor prognosis in several tumor types [20] (Figure 1D).